This is an extremely jaundiced statement and you know it. As for characters who she struggles with that aren't clearly definsed speedsters, look at Kirby or Yoshi. Hitting Kirby as Zelda safely is particularly difficult because of how small he is in addition to his crouch making most of your moves whiff. Good recovery isn't much of a unique trait to Zelda because most Brawl based recoveries are great in general, with Smash4 being no exception. It cannot be ignored that Zelda's recovery is only safe/good for grabbing the edge, and that clearing the edge safely after grabbing it is not as safe as it used to be. There are other recoveries like Rosalina's or Lucario's that will both grab the edge quickly and allow you to clear the stage in a safe position depending on what you need.
wtf, most of the recoveries in this game are honestly not that good. Only about 10 characters or so have seriously good recoveries who are like Sonic, Pikachu, Villager, Greninja, Mr Game and Watch, Peach, Metaknight, Samus, Zero Suit Samus, and Zelda. Basically everyone else has to play around ledgeguards respectfully. Zelda having one of the best recoveries in the game is a huge asset that can't be denied especially when it lets you get out of traps and edgeguard people.
Zelda's recovery is STRICTLY superior to Rosalina's. I don't even know how you came to a different conclusion when Rosalina literally can be intercepted by any lingering hitbox, and also has to play very carefully around ledge steals. Rosalina gets good distance but like everyone else has to play respectfully against edgeguard attempts. Zelda gets like similar distance as Rosalina does on Up-B except you reach the ground sooner when recovering from the ledge, making Zelda one of the hardest characters in the game to ledge trap period.
Lucario's recovery? Okay, he gets a good one post Aura buffs, not going to argue that.
As for Kirby, he can crouch, but I don't think he's winning a D-tilt war against Zelda, and he has to play respectfully against pivot grab and Dash Attack which can check a lot of his stuff in the air, and Zelda has a much easier time edgeguarding him than the other way around. Not sure why you specifically think Zelda has trouble with him. As for Yoshi, you might know better than me, but I'm pretty certain not only does he not actually have good normals for directly challenging several of Zelda's attacks (he's not a very disjointed character in general), he has to play respectfully around Naryus and Phantom unless I missed something, and most of his aerial attacks aren't that good fullhopped, so I'm not totally seeing how that's a particularly bad matchup for Zelda. He's not Peach who has floating. He has to land semi-predictably and his aerials typically are only effective at low altitudes.
Zelda's normals are merely okay. Her multihits that aren't Nayru's Love are still plagued with inconsistency issues. Good tier placement means a good matchup spread and fewer "headache" matchups. Of course other characters have them, but they're comparatively better balanced than Zelda to run into fewer of them. Zelda has more than a few polarizing matchups against her, and honestly not enough for her. This becomes evident when you're not tunnel visioning one character and use other characters the game has to offer and notice different levels of overall performance. Even if you insist that "Zelda can do well," if the majority of other characters' tool kits are competitively better off than Zelda, then Zelda will wind up as a low tier by a matter of relativity. That much is an indisputable fact for any character's placement in a tier list.
relativity? I'm trying to factor what Zelda has compared to other characters, and what bad matchups she probably has. You can be mid tier and have some lame matchups, while being competent in several other relevant ones. Unless I'm mistaken, I don't see why Zelda shouldn't do well against Lucario and Rosalina for instance, and I also don't believe Yoshi is as hard for Zelda as you suggested. The primary three that look really hard are Sonic, Little Mac, and Peach who kinda can disrespect Zelda's footsies in obvious ways.
I used to be a big "princess fan" in Smash Bros. but I got a dose of reality and grew out of that phase. Zelda really didn't change so drastically from Brawl to Smash4 to warrant huge jumps in placement aside from recovery mechanics, which honestly brings up a lot of recoveries that were previously considered poor. That alone isn't enough to make her well off in potential tier placement when she still retains many of the issues that kept her in low/bottom tiers.
Realistically, Zelda benefits a huge amount more than most other characters with "poor" recoveries because she actually can edgeguard very well in this game. Not to mention she dodges one of the negative side effects of ledge mechanics very easily, which is ledge trapping, while other characters have to take riskier guesses to get back into neutral.
Most of the cast in this game got nerfed, while Zelda in most ways is strictly a buffed character and actually got tools that redefine her gameplan and options (viable grab, actually is now a very difficult character to edgeguard and trap while in Brawl this wasn't quite the case, able to chase landings much better in this game). I'm pretty sure she has easier matchup spreads than close to half the cast of the game, though I guess we'll have to see later.
I don't even consider myself a big Zelda fan, and I've been trying to look up every character in this game. Just when you consider what the whole game is about, Zelda fits the metagame really well and doesn't have to put up with a lot of nonsense that would normally drive a lot of characters insane. Okay she has trouble against really fast characters and fullhop spacing? A lot of characters do, but not everyone gets out of traps easily or can threaten landings to the same extent Zelda can, and having a reflector on top of that is really nice in a game where a lot of the best characters are able to projectile zone in some way.